Zhou Yan, Perkins Luke A, Wang Guodong, Zhou Dongsheng, Liang Hong
Materials Science and Engineering, Texas A&M University, College Station, TX 77843, USA.
Mechanical Engineering, Texas A&M University, College Station, TX 77843, USA.
J Funct Biomater. 2015 Oct 15;6(4):1012-20. doi: 10.3390/jfb6041012.
Internal fixations provide fast healing but their failure remains problematic to patients. Here, we report an experimental study in failure of three typical cases of metals: a bent intramedullary stainless steel nail, a broken exterior pure Ti plate, and a broken intramedullary stainless steel nail. Characterization of the bent nail indicates that those metals are vulnerable to corrosion with the evidence of increased surface roughness and embrittlement. Depredated surface of the Ti plate resulted debris particles in the surrounding tissue of 15.2 ± 6.5 μm in size. Nanoparticles were observed in transmission electron microscope. The electron diffraction pattern of the debris indicates a combination of nanocrystalline and amorphous phases. The failure mode of the broken nail made of stainless steel was found to be fatigue initiated from the surface. This study clearly shows the biological-attack induced surface degradation resulting in debris and fatigue. Future design and selection of implant materials should consider such factors for improvement.
内固定能实现快速愈合，但内固定失败对患者来说仍然是个问题。在此，我们报告一项关于三种典型金属病例失败情况的实验研究：一根弯曲的不锈钢髓内钉、一块断裂的外部纯钛板和一根断裂的不锈钢髓内钉。对弯曲钉子的表征表明，这些金属容易受到腐蚀，证据是表面粗糙度增加和脆化。钛板表面受损产生了尺寸为15.2±6.5μm的碎片颗粒，在周围组织中发现了这些颗粒。在透射电子显微镜下观察到了纳米颗粒。碎片的电子衍射图谱表明其为纳米晶相和非晶相的组合。发现由不锈钢制成的断裂钉子的失效模式是从表面开始的疲劳。这项研究清楚地表明，生物攻击会导致表面降解，进而产生碎片和疲劳。未来植入材料的设计和选择应考虑这些因素以进行改进。
